The goal of this project was to introduce the concept of persona to the history of science, by showing how it can be fruitfully deployed in diverse periods, locales, and disciplines. Intermediate between the individual biography and the social institution lies the persona: a cultural identity that simultaneously shapes the individual in body and mind and forges a collective with a shared and recognizable physiognomy. Personae are creatures of historical circumstance; they emerge and disappear within specific contexts. A nascent persona indicates the creation of a new kind of individual, whose distinctive traits mark a recognized social species. The members of the group on "The Scientific Persona" traced the emergence of various scientific personae, where "scientific" is understood broadly enough to embrace the instrument maker, the scholar, the technocrat, and the professor, as well as the experimenter and the naturalist. Although the chronological center-of-gravity was the nineteenth century, the period during which new words like "scientist," der Naturwissenschaftler, le scientifique were coined for a group that laid claim to ever greater cultural recognition, the topics pursued by members of the research group spanned the Pre-Socratics through the twentieth-century physicist. In the same comparative spirit, cases in Britain, France, Italy, Germany, and the United States, as well as disciplines ranging from physics to botany to astronomy to philology were studied. The aim was to investigate the personal element in science not as biographers but more as botanists, piecing together a type specimen that represents a class rather than any individual in particular.